(1) Field of the Invention
The present invention relates generally to optical sliprings, and more particularly to a multi-line, fiber optic slipring that is constructed from passive components.
(2) Description of the Prior Art
Present devices used to pass multiple fiber optic lines through a rotating joint generally comprise one of two types. The first type is a passive device known as a coiled ribbon slipring which places optical fibers parallel to each other to form a ribbon cable. The ribbon cable is coiled around the slipring's axis of rotation. One end of the cable is connected to the stationary side of the slipring, while the other end is connected to the rotating side of the slipring. The advantage of this device is that it can pass multiple fiber optic lines through a rotating joint without the use of active conversion devices (e.g., optical-to-electrical conversion devices). However, this type of device is limited to a specific number of rotations determined by the number of times the cable is coiled around itself.
The second type of prior art optical slipring is an active conversion device in which signals from multiple fiber optic lines pass through a rotating joint by using devices that convert the optical signals into electrical signals, send the electrical signals through the joint using conventional electrical slipring methods, and then convert the electrical signals back into optical signals. This type of slipring has the advantage of an unlimited number of rotations, but has several disadvantages in that (1) power is needed to operate the active conversion devices, (2) electrical noise and electromagnetic interference may be introduced, and (3) cross talk between channels may occur.